Embodiments of the present inventive concept relate to a data storage device, and more particularly to a device which is capable of generating a pseudo noise (PN) sequence using logical information and physical information, and processing data using the PN sequence.
Pseudo random numbers are used in some communication systems and data storage systems. The pseudo random numbers are used to generate a pseudo random number sequence.
A linear feedback shift register (LFSR) is used to generate the pseudo random number sequence or the pseudo noise sequence. The LFSR changes the pseudo random number sequence by changing an initial value referred to as a seed or seed value, or by changing feedback taps.
A randomizer converts data into randomized data using the pseudo random number sequence generated by the LFSR. A de-randomizer also converts the randomized data into de-randomized data using the pseudo random number sequence generated by the LFSR. The randomness of the pseudo random number sequence has to be ensured.
In order to develop a cheap flash memory with high density, studies for scaling down size and for providing a multi-level cell (MLC) have been actively progressing.
Since coupling or disturbances between adjacent multi-level cells becomes more pronounced as the scaling down proceeds or the multi-level cell stores more bits, the threshold voltage distribution is deteriorated.
A copy back operation denotes an operation of copying data of a specific page to another page in a flash memory cell array.
According to whether the copy back operation on data of a specific page in a flash memory cell array is performed inside or outside the flash memory cell array, the copy back operation may be classified into internal copy back or external copy back. Performance of a copy back operation using internal copy back is generally better than performance of a copy back operation using external copy back.
In case of an internal copy back operation, data randomness of a buffer block (e.g., single level cell (SLC)) is easy to ensure. However, since it is hard to estimate into which multi-level cell block data of the buffer block is merged, data randomness of a multi-level cell block is difficult to ensure.